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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Plant pathology 39 (1990), S. 0 
    ISSN: 1365-3059
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: The distribution of restriction-fragment-length polymorphisms (RFLPs) among isolates of Erysiphe graminis f.sp. hordei was used to test hypotheses about the structure of the pathogen population. There was a large diversity in the lengths of DNA restriction fragments homologous to E9, a chromosomal fragment of unknown function. It was shown that a large group of isolates, which shared identical or very similar virulence phenotypes, including virulence on the barley cv. Triumph, were members of a single clone. Several other clones were identified, including a second group of identical isolates which were virulent on cv. Triumph but were highly distinct from the more common clone of Triumph-virulent isolates. Isolates which shared the same level of resistance to the triazole fungicide triadimenol were genetically diverse. Such diversity is consistent with triadimenol resistance being under oligogenic, rather than polygenic, control. Conclusions obtained from analysis of the most easily identifiable subset of fragment lengths were very similar to those obtained from analysis of the complete set.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Plant pathology 38 (1989), S. 0 
    ISSN: 1365-3059
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: DNA isolated from the formae speciales of Erysiphe graminis that grow on barley, wheat, rye and oats was studied using restriction endonucleases and DNA/DNA hybridization procedures. DNA fragments were purified by molecular cloning and a few containing repeated sequences were used to demonstrate the many variations in restriction fragments both within and between the fourformae speciales. In an analysis of six single-colony isolates of the barley mildew pathogen collected from different UK sites in different years, more than a quarter of the fragments scored varied among isolates. One isolate, with an uncommon pathogenicity character, differed from the remainder in the distribution of DNA bands. Isolates of rye mildew were also distinct from one another but isolates of oat mildew from a population of similar size appeared to belong to a single clone.It is concluded that the chromosomes of E. graminis contain many families of dispersed repeated sequences and that there may be extensive polymorphism for restriction endonuclease cleavage sites associated with these repeats. Such unselected polymorphisms could be useful in helping to understand and discriminate among the factors affecting population structure in the pathogen as it responds to different agricultural practices.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 288 (1980), S. 133-137 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] A simple repeating unit of the rye genome, previously known in tandem arrays, has now been shown to occur also in more complex repeating units. One such unit has been cloned and found to contain some sequences unrelated to the simple repeat. It is proposed that tandem arrays of complex repeats are ...
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Analytica Chimica Acta 23 (1960), S. 503-504 
    ISSN: 0003-2670
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Analytica Chimica Acta 23 (1960), S. 503-504 
    ISSN: 0003-2670
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Analytica Chimica Acta 23 (1960), S. 503-504 
    ISSN: 0003-2670
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Cellular and molecular life sciences 17 (1961), S. 217-218 
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Zusammenfassung Behandlung von Kreatinphosphokinase mit überschüssigemN-Bromsuccinimid bewirkt eine Umwandlung der vorhandenen peptidartig gebundenen Tryptophanreste, welche sich durch die für diesen Vorgang charakteristische Veränderung des Spektrums anzeigt. Am unbehandelten Enzym liessen sich auch mit einem grossen Überschuss von NBS keine freien endständigen NH2-Gruppen eindeutig nachweisen.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Two pairs of chromosomes (1U and 5U) in Aegilops umbellulata possess ribosomal RNA genes. This has been proven by studying wheat plants into which 1U and 5U chromosomes have been introduced separately. These plants have more ribosomal RNA genes than the recipient wheat plants and additional clusters of rDNA when examined by in situ hybridisation. The repeating rDNA unit in Aegilops umbellulata is longer than most of the units in the wheat variety Chinese Spring, the additional DNA probably being in the non-transcribed spacer. This was determined from restriction endonuclease maps of rDNA. In Chinese Spring plants possessing 1U or 5U chromosomes, the largest nucleoli are formed on 1U or 5U chromosomes and the wheat nucleolus organisers form micronucleoli. This is not because the nucleolus organisers on chromosomes 1U and 5U have many more rRNA genes than wheat nucleolus organisers. It is suggested that the Aegilops umbellulata nucleolus organisers are dominant over those of wheat because they compete more effectively for some limiting factor. — The partial inactivation of the wheat nucleolus organisers by chromosomes 1U or 5U does not result in a reduced total nucleolus volume in root tip or pollen mother cells, because of the compensation by the nucleolus organisers of chromosomes 1U or 5U. The amount of RNA in seedlings is not markedly affected by the partial inactivation of the wheat nucleolus organisers.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1432-2242
    Keywords: Intrachromosomal mapping ; Nucleolar organiser region ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Restriction enzyme digestion of the ribosomal RNA genes of the nucleolar organisers of wheat has revealed fragment length polymorphisms for the nucleolar organiser on chromosome 1B and the nucleolar organiser on 6B. Variation between genotypes for these regions has also been demonstrated. This variation has been exploited to determine the recombination frequency between the physically defined nucleolar organiser on 1B (designatedNor1) and other markers; two loci,Glu-B1 andGli-B1 which code for endosperm storage proteins andRf3, a locus restoring fertility to male sterility conditioned byT. timopheevi cytoplasm.Gli-B1 andRf3 were located on the short-arm satellite but recombine with the nucleolar organiser giving a gene order ofNor1 — Rf3 — Gli-B1. Glu-B1 is located on the long arm of 1B but shows relatively little recombination withNor1, which is, in physical distance, distal on the short arm. This illustrates the discrepancy between map distance and physical distance on wheat chromosomes due to the distal localisation of chiasmata. The recombination betweenNor1 andRf3 indicates that, contrary to previous suggestions, fertility restoration is not a property of the nucleolar organiser but of a separate locus.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Molecular genetics and genomics 255 (1997), S. 294-301 
    ISSN: 1617-4623
    Keywords: Key words Nucleolar dominance ; Nucleolar organizer region ; Methylation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In wheat-rye hybrids the nucleolus organizer regions (NORs), the sites of ribosomal RNA genes, from rye are suppressed. Wheat and wheat-rye hybrid genetic stocks containing different numbers of wheat and rye nucleolus organizers, as well as addition lines and rye-barley hybrids, were used in Southern hybridization experiments to determine the cause of nucleolar dominance and suppression in cereal hybrids. Based on the use of restriction endonucleases that cleave near the ends of the spacer unit and an additional, methylation-sensitive enzyme, HpaII, which does not recognize the CCGG restriction site if the internal C is methylated, an indirect method of assaying NOR expression was established. The results indicated that cleavage by the HpaII enzyme of the rye NOR sequences, is reduced when major NORs from other cereals were present. The reduction in the number of rye rRNA genes containing an unmethylated CCGG site in the promoter was associated with the suppression of the rye nucleolus. These results are consistent with a model in which promoter and upstream regulatory repeats of ribosomal RNA genes compete for limited concentrations of regulatory proteins, and genes that are methylated at key binding sites fail to engage these regulatory proteins and thus remain inactive.
    Type of Medium: Electronic Resource
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